C++ :

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>

using namespace std;

double f[151][151],m[151],minx,r,temp,x[151],y[151],maxint=1e12;
double dist(int i,int j)
{
	return sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
}

int main()
{
    int i,j,n,k;
	char c;
	
	cin >> n;
	for (i = 1; i <= n; i++)
	{
		cin >> x[i] >> y[i];
	}   
	for (i = 1; i <= n; i++)
	 for (j = 1; j <= n; j++)
	 {
	 	cin >> c;
	 	if(c=='1')
	 	{
	 		f[i][j]=dist(i,j);
	 	}
	 	else
	 	{
	 		f[i][j]=maxint;
	 	}
	 }
	for(k = 1; k <= n; k++)
		for(i = 1; i <= n; i++)
			for(j = 1; j <= n; j++)
				if(i!=j && i!=k && j!=k)
					if(f[i][k]<maxint-1 && f[k][i]<maxint-1)
						if(f[i][j]>f[i][k]+f[k][j])
							f[i][j]=f[i][k]+f[k][j];
	memset(m,0,sizeof(m));
	for(i=1;i<=n;i++)
	for(j=1;j<=n;j++)
	if((f[i][j]<(maxint-1))&&(m[i]<f[i][j]))
	m[i]=f[i][j];
	minx=1e20;
	for (i = 1; i <= n; i++)
	 for (j = 1; j <= n; j++)
	 	if(i!=j && f[i][j]>maxint-1)
	 	{
	 		temp=dist(i,j);
	 		if(minx>m[i]+m[j]+temp)minx=m[i]+m[j]+temp;
	 	}
	r=0;
	for (i = 1; i <= n; i++)
		if(m[i]>minx)
		minx=m[i];
		printf("%0.6lf",minx);
    return 0;
}